Did you mean Netbeans? Or was it some other IDE that we (on the forums) do not support?

phamthao wrote:
..I am trying to read string from text file but i do not know why in netbean result is "File not found !" (file not found exception)
but in JCreator result is all text in file.

Obviously the two environments are different. But since nobody here provides support for Netbean, netbean, Netbeans or JCreator, you are out of luck unless you intend to figure this out using either:
a) The SDK tools used from the command line, or
b) An Ant build script, which is usually just a thin veneer over the SDK tools we might use from the command line.